Stencil screen and method of making the same



Patented Mar. 6, 1945- STENCIL SCREEN AND METHOD OF MAKING THE SAME Harry E. Playford, Sapulpa, kla., assignor to The Liberty Glass Company, Sapulpa, 0kla., a

corporation No Drawing. Application March 16,1942.

Serial No. 434,935

2 Claims.

This invention relates to stencil screens and to a method of making the same.

Heretofore it has been the-practice to utilize stainless steel wire or silk in the formation of these screens but because of the comparatively higher cost or uncertainty of obtaining these materials, it has been found desirable to use substitutes. Silk, when moistened, will shrink and, therefore, has been an excellent material for use on a stencil frame in lieu of wire mesh. The most desirable, readily obtainable, and cheaper substitutes for silk are rayon and nylon. Fabrics of these materials, however, will stretch when moistened and as the preparation of a stencil screen of necessity involves the steps of (1) sizing; and (2) transferring while in a moist state, of light sensitive material onto the fabric, said fabrics necessarily become moist and will stretch if the usual procedure is followed; thus causing undesirable sagging of the finished stencil screen.

Furthermore nylon and rayon are nonabsorbent and ordinarily will not respond to the impregnation or attraction treatment to which steel wire is subjected nor absorb as readily as silk. Consequently these materials could not be used efiiciently heretofore.

An object of the present invention is to so treat the nylon, rayon or other synthetic fabric as to prevent excessive sagging Or stretching after the screen has been attached to its frame and permit efiicient use thereof in building up a backing for a stencil pattern or design, and eflicient use of the screen in stenciling.

With the foregoing and other objects in view the invention resides in certain novel steps in the method of treatment and in the resultant After the dry fabric has been attached to an expanding temporary support or has been stretched while moist, fastened to a permanent stencil support and allowed to dry, it is treated with liquid gelatin sizing or the like containing light sensitive material, and again allowed to dry.

A sheet of light sensitive gelatin (potassium dito the gelatin. The result is attained by placing 1 should be made to exclude light and can be product hereinafter more fully described and pointed out in the claims. it being understood that changes may be made within the scope of the claims without departing from the spirit of the invention.

In producing photo-gelatin and photo-polyinyl alcohol, or other light sensitive material screens usin nylon or other synthetic fabrics, a pieceof dry fabric of proper dimensions can be fastened to a temporary expansible support of any suitable construction so as to be stretched when moistened and after being moistened and stretched, the fabric can be tacked or otherwise fastened to the permanent stencil support. In lieu of the foregoing step wet fabric can be stretched over and fastened to the permanent stencil support, thereby eliminating the use of a temporary support for the stretching operation.

heated .electrically while moisture can, be supplied by boiling water in the enclosure, and the desired temperature and humidity can be attained by ventilation or by an automatic humidifier.

It has-been found that a synthetic fabric, such as nylon and rayon, treated as herein explained will not sag after the exposure and washing out process if dried normally or by drying means at a temperature of approximately to F.

Importance is attached to the fact that the fabric is stretched while moist before it is atmaterial stencil screen with a synthetic mesh fabric of a type which will stretch when moistened, which includes the step of moistening the fabric, stretching the fabric while moist, attach-' ing the stretched fabric to a supporting frame and drying the fabric, thereafter treating the stretched fabric with gelatin sizing and drying it, then applying a sheet of light sensitive gelatin ing atmosphere.

2. The method of preparing a light sensitive stencil screen with a synthetic mesh fabric of a type which will stretch when moistened, which includes the step of moistening the mesh fabric to render it stretchable, stretching the fabric while moist, attaching the stretched fabric to a sup- 10 t .onto the screen, and

porting frame and drying the fabric, thereafter subjecting the stretched, dried fabric to a gelatin size, again drying the screen, thereafter transferring a sheet of moist light sensitive gelatin then subjecting the materials to a temperature of approximately 90 F. while exposeclto a humidity of approximately 45%, thereby to fuse the fabric, size and sheet gelatin into a unitary sheet.

HARRY E. PLAYFORD. 

